Plasma processing apparatus

ABSTRACT

The object of the invention is to provide a plasma processing apparatus having enhanced plasma processing uniformity. The plasma processing apparatus comprises a processing chamber  1 , means  13  and  14  for supplying processing gas into the processing chamber, evacuation means  25  and  26  for decompressing the processing chamber  1 , an electrode  4  on which an object  2  to be processed such as a wafer is placed, and an electromagnetic radiation power supply  5 A, wherein at least two kinds of processing gases having different composition ratios of 0 2  or N 2 are introduced into the processing chamber through different gas inlets so as to control the in-plane uniformity of the critical dimension while maintaining the in-plane uniformity of the process depth.

The present application is based on and claims priority of Japanesepatent application No. 2004-217118 filed on Jul. 26, 2004, the entirecontents of which are hereby incorporated by reference. This applicationis Divisiional of prior application No. 10/911,610, file Aug. 5, 2004,the contents of which are hereby incorporated herein by reference inthier entirety.

FIELD OF THE INVENTION

The present invention relates to a plasma processing apparatus used inthe fabrication of semiconductors.

DESCRIPTION OF THE RELATED ART

Heretofore, plasma etching utilizing weakly-ionized plasma is adoptedwidely in the process of fabricating a semiconductor device such as aDRAM or a microprocessor. Now, FIG. 10 is referred to in explaining themechanism of etching, taking the etching of an SiOC film as an example.A mixed gas containing CHF₃, CF₄ and N₂ is used as the processing gas,for example. Radicals such as CF and CF₂ dissociated from CHF₃ and CF₄in the plasma are deposited on the SiOC 51 and resist 52, forming adeposition film 53. Then, the ions generated in the plasma areaccelerated by bias power to be incident on the object to be processed,by which energy is applied to the interface between the SiOC 51 and thedeposition film 53, causing reaction of the SiOC 51 and the depositionfilm 53 and progressing etching.

The finishing contour formed after etching depends not only on theenergy and variation of ions being incident on the object to beprocessed but also on the thickness and composition of the depositionfilm. For example, according to conditions where the deposition filmbecomes excessively thick or conditions where considerable amount ofcomponents such as C that inhibit etching are contained in thedeposition film, the etching rate is deteriorated or the etching isstopped before it is completed. This is because the ions being incidenton the object to be processed cannot easily reach the interface betweenthe deposition film and SiOC. Moreover, if the deposition film depositedon the side walls of the holes or trenches becomes excessively thick,the etching of the side walls of the holes and trenches may besuppressed excessively, causing the processed bottom portion of theholes and trenches to have a narrowed tapered shape. Oppositely, if thedeposition film is too thin, the lack of deposition film to be reactedwith SiOC deteriorates the etching rate. According to the exampleillustrated in FIG. 10, the thickness and composition of the depositionfilm depends mainly on the balance of deposition of radicals such as CFand CF₂ radicals dissociated from CHF₃ and CF₄, the deposition ofreaction products generated by the etching and being incident on theobject again, the removal of the deposition film by the N radicalsdissociated from N₂, and the consumption of the deposition film alongwith the progression of etching.

The mechanism of etching has been described by taking as an example theetching of SiOC film using CHF₃, CF₄ and N₂, but in etching SiO₂ or SiOFfilms, for example, a process gas containing Ar, CF-based gas such asC₄F₆ or C₅F₈ and O₂ is used. In this case, radicals such as CF and CF₂dissociated from C₄F₆ or C₅F₈ contribute to the generation of thedeposition film, and O radicals dissociated from O₂ function to removethe deposition film.

Next, the general outline of a plasma processing apparatus is describedwith reference to the example illustrated in FIG. 11. The presentapparatus is a parallel plate plasma etching apparatus, having equippedin a processing chamber 1 a substantially disk-like antenna 3 forelectromagnetic radiation and an electrode 4 on which an object 2 to beprocessed is placed, which are disposed in parallel and facing eachother. An electromagnetic radiation power supply 5A for generatingplasma is connected to the antenna 3 via a matching network 6A.

Below the antenna 3 is disposed a shower plate 11. Processing gases aresupplied from gas cylinders 20, which are adjusted to predetermined flowrates via gas flow controllers 13, and introduced through gas holesprovided to the shower plate 11 to the processing chamber 1. Moreover,in order to control the radical distribution within the plasma, it ispossible to introduce processing gases having different compositions orflow rates through the inner area and the outer area of the shower plate11. An RF power supply 5C is connected to the electrode 4 via a matchingnetwork 6C, by which the ions being incident on the object 2 isaccelerated to etch the object.

There has already been proposed a parallel plate electrode-type RIEapparatus in which a stage electrode and a gas supply electrode aredisposed in confronting relationship in the etching chamber to realizeuniform etching of a large-diameter wafer, wherein the gas supplysurface of the gas supply electrode is divided into three areas, a firstgas supply area, a second gas supply area and a third gas supply area,and the gas supply to each gas supply area is controlled independentlythrough a first gas flow rate control system, a second gas flow ratecontrol system and a third gas flow rate control system, respectively.Thereby, the flow rate of etching gas and the flow ratio of gases havingdifferent ionization potential to be supplied via the first, second andthird gas supply areas are optimized (refer for example to patentdocument 1).

Moreover, the present applicant has filed a patent applicationdisclosing a plasma etching apparatus comprising a processing chamberfor performing plasma etching to an object to be processed, a first gassupply source for supplying processing gas, a second gas supply sourcedisposed independently from the first processing gas, a first gas inletfor introducing the processing gas into the processing chamber, a secondgas inlet disposed independently from the first gas inlet, a flowcontroller for controlling the flow rate of the processing gas, and agas flow divider for dividing the process gas into plural flows, whereinthe second gas is supplied between the gas flow divider and at least oneof the first or second gas inlets so as to supply the processing gas viatwo systems (refer for example to patent document 2).

[Patent document 1]

-   -   Japanese Patent Application Laid-Open No. 2002-184764        [Patent document 2]    -   Japanese Patent Application No. 2003-206042

In order to perform uniform etching across the plane of an object suchas a wafer, the in-plane distribution of ions being incident on thesurface of the object (plasma distribution) and the thickness andcomposition of the deposition film being deposited on the object must beuniform across the plane of the object. The conventional plasmaprocessing apparatus mentioned earlier is equipped with a means forcontrolling the plasma distribution and radical distribution in order tocarry out uniform plasma processing across the plane of the object.However, the process dimension regarded important in the fabrication ofsemiconductor devices include the process depth and the criticaldimension (CD), and according to the prior art plasma processingapparatus, the in-plane uniformity of the process depth and the in-planeuniformity of the critical dimension could not be controlledindependently. Here, critical dimension (CD) refers for example to thewidth of a trench, a width of a line or a diameter of a hole in themicro pattern formed on the object being processed. Therefore, thein-plane uniformity of the critical dimension may be deteriorated byenhancing the in-plane uniformity of process depth, so it is necessaryto seek the process conditions that fulfill both the in-plane uniformityof process depth and in-plane uniformity of critical dimension throughtrial and error, by adjusting little by little the flow rate andcomposition of the process gases supplied through the inner area andouter area of the shower plate, the bias power and the discharge power.

Compared to the process depth, the critical dimension depends greatly onthe thickness and composition of the deposition film, so it ispreferable that the in-plane distribution of the critical dimension beuniformized without changing the uniformity of process depth byappropriately controlling the thickness and composition of thedeposition film. Since the method for controlling the composition andflow rate of gases being introduced through the inner gas holes and theouter gas holes of the shower plate allows a large degree of freedom ofradical distribution control, the method is promising as a way forappropriately controlling the thickness and composition of thedeposition film.

SUMMARY OF THE INVENTION

In consideration of the above-mentioned problems, the present inventionaims at providing a plasma processing apparatus that optimizes the gassupply system thereof to enable the process depth uniformity and thecritical dimension uniformity of the object to be controlledindependently, or in other words, to enable the critical dimension to becontrolled without changing the process depth uniformity.

The present invention provides a plasma processing apparatus comprisinga processing chamber, a means for supplying processing gas to theprocessing chamber, an evacuation means for decompressing the processingchamber, an electrode on which an object to be processed is placed, andan electromagnetic radiation power supply, wherein at least two kinds ofprocessing gases having different flow ratio or O₂ or N₂ compositionratio are introduced from different gas inlets to thereby uniformize thecritical dimension across the plane of the object while maintaining auniform process depth across the plane of the object.

Furthermore, according to the present invention, process gases otherthan O₂ and N₂ are divided into plural flows as first processing gas,and O₂ and N₂ are added as second gas to the first gas having beendivided, so that processing gases having different O₂ or N₂ compositionor different flow rate can be introduced through different gas inletsinto the processing chamber. At this time, regardless of the amount ofO₂ or N₂ to be added to the first gas having been divided into pluralflows, a gas distributor for dividing the first gas into plural flows isused to divide the first processing gas into predetermined flow ratios.

Moreover, the present invention is equipped with a gas distributor fordividing O₂ or N₂ into predetermined flow ratios in order to add the O₂or N₂ of predetermined flow ratios to the divided first gas.

Further, the present invention characterizes in disposing gas flowmeters between the first gas outlet provided in the processing chamberand the gas distributor and between the second gas outlet provided inthe processing chamber and the gas distributor, so as to monitor whetherthe gas distributors are operating normally.

Even further, the present invention characterizes in connecting gaslines for evacuating processing gases without passing through theprocessing chamber between the first gas outlet provided in theprocessing chamber and the gas distributor and between the second gasoutlet provided in the processing chamber and the gas distributor, so asto check whether the gas distributors are operating normally.

According further to the present invention, an O-ring is used to dividethe gas dispersion plate for dispersing processing gases into a firstgas dispersion area and a second gas dispersion area, and the dispersionplate is screwed onto the antenna or a top panel so that it will not belifted by the O-ring and that the O-ring stays in position.

Moreover, the present invention characterizes in that the gas holesprovided to the shower plate are arranged substantially concentrically,so that the gas holes of the shower plate do not overlap with theposition of the O-ring.

Even further, the present invention characterizes in that the area fordispersing the second gas an the gas dispersion plate isdoughnut-shaped, and in order to uniformly disperse the gas in thedoughnut-shaped area, plural gas outlets for ejecting the secondprocessing gas onto the dispersion plate is arranged substantiallycircumferentially.

As explained, according to the present invention, at least two kinds ofprocessing gases having different O₂ or N₂ composition ratios ordifferent flow rates are introduced through different gas inlets atpredetermined flow rate and composition into the processing chamber, tothereby uniformize the critical dimension across the plane of the objectindependently from the in-plane uniformity of the process depth. Thus,the uniformity of both the process depth and the critical dimensionacross the plane of the object can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view showing a first embodiment in which thepresent invention is applied to a parallel plate ECR plasma etchingapparatus;

FIG. 2 is an explanatory view showing that the process depth uniformityand critical dimension uniformity across the object plane can becontrolled independently;

FIG. 3 is an explanatory view showing the gas flow according to the gassupply system when introducing gases having the same composition fromthe inner and outer gas holes;

FIG. 4 is an explanatory view showing the gas flow according to the gassupply system when the amount of N₂ to We Introduced through the innergas holes is greater than the amount of N₂ to be introduced through theouter gas holes;

FIG. 5 is a schematic view of a second embodiment in which the presentinvention is applied to a parallel plate ECR plasma etching apparatus;

FIG. 6 is an explanatory view of a third embodiment in which the presentinvention is applied to a CCP plasma processing apparatus;

FIG. 7 is a partially enlarged view of FIG. 6;

FIG. 8 is an explanatory view showing the structure of the antenna;

FIG. 9 is an explanatory view of a fourth embodiment in which thepresent invention is applied to a CCP plasma processing apparatus;

FIG. 10 is an explanatory view showing the mechanism of etching; and

FIG. 11 is an explanatory view showing the parallel plate plasmaprocessing apparatus according to the prior art.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Now, a first preferred embodiment of the present invention will beexplained with reference to the drawings. FIG. 1 illustrates the firstembodiment in which the present invention is applied to a parallel-plateECR plasma processing apparatus. A substantially disk-shaped antenna 3for electromagnetic radiation and an electrode 4 parallel to and inconfronting relation with the antenna 3 on which an object 2 to beprocessed is placed are disposed in a processing chamber 1. Anelectromagnetic radiation power supply 5A for plasma generation isconnected to the antenna 3 via a matching network 6A. The frequency ofthe electromagnetic radiation power supply 5A is set for example to 100through 450 MHz. A coil 8 and a yoke 9 are disposed outside theprocessing chamber 1 for generating a magnetic field. The presentapparatus is capable of generating plasma efficiently through theinteraction of magnetic field and electric field, and also capable ofcontrolling the plasma generating position or plasma transport byadjusting the magnetic field distribution.

A shower plate 11 is placed below the antenna 3 via a dispersion plate10. The material of the shower plate 11 is Si. Apart from theelectromagnetic radiation power supply 5A, the antenna 3 is connected toan RF power supply 5B via a matching network 6B, through which theplasma distribution and radical distribution of F or the like can becontrolled. The frequency of the RF power supply 5B can be set from afew hundred kHz to a little over ten MHz.

According to the present apparatus, the area above the antenna isatmospheric, so an O-ring 21 is disposed to seal the antenna 3 and aquartz member 28.

An RF power supply 5C is connected to the electrode 4 via a matchingnetwork 6C so as to control the flux or energy of ions being incident onthe object 2 to be processed. The FRF power supply has the samefrequency as the RF power supply 5B, and the RF power generated by theRF power supply 6C is set to be in opposite phase to that of the RFpower supply 6B through use of a phase controller 7, according to whichthe confinement of plasma is enhanced. The electrode 4 can be moved inthe vertical direction, and the plasma distribution and radicaldistribution can be controlled by adjusting the distance between theantenna 3 and the electrode 4.

A refrigerant is set to flow within the electrode 4 (not shown) tocontrol the temperature of the object 2 to be processed. Moreover, thesurface of the electrode 4 is provided with a groove that allows heliumto flow through between the back surface of the object 2 and theelectrode so as to cool the object. Moreover, the flow path of helium isdivided into two parts, the inner area and the outer periphery of theelectrode, so as to control the temperature of the object to beprocessed independently at the inner area and the outer periphery of theobject. Helium can be supplied to the inner area and to the outerperiphery of the electrode at different flow rates via a helium inletpassage 16-1 for supplying helium to the inner area of the electrode anda helium inlet passage 16-2 for supplying helium to the outer peripheryof the electrode.

In order to secure the object 2 to be processed to the electrode 4 viaelectrostatic chuck, a dipole power supply (not shown) is connected tothe electrode 4. The processing chamber is set to earth potential.

Processing gas is fed to the processing chamber 1 through theelectromagnetic radiation antenna 3, the gas dispersion plate 10 and theshower plate 11. The shower plate 11 has multiple gas holes providedthereto. The gas holes are arranged substantially concentrically, forexample, with 10 mm intervals within a 300 mm diameter area.

The gas dispersion plate 10 is separated by a substantially ring-shapedpartition 12 for controlling the radical distribution in the plasma,enabling processing gases having different compositions or differentflow rates to be introduced via gas holes of the shower plate 11positioned in the inner area of the ring-shaped partition 12(hereinafter called “inner gas holes”) and gas holes of the shower plate11 positioned outside the ring-shaped partition 12 (hereinafter called“outer gas holes”). An O-ring can be used for example as the ring-shapedpartition 12, and the inner diameter of the ring-shaped partition isbetween approximately 50 through 250 mm.

The processing gases introduced to the processing chamber 1 can include,for example, Ar, CHF₃, CH₂F₂, CH₄, C₄F₆, C₄F₈, C₅F₈, CO, O₂ and N₂. Ofthe listed processing gases, Ar, CH₄, C₄F₆, C₄F₈, C₅F₈, CHF₃, CH₂F₂ andCO can be supplied via gas flow controllers 13-1 through 13-8 atpredetermined flow rates to reach a first gas distributor 14-1. Thegases that have reached the first gas distributor 14-1 are called afirst gas. The first gas is divided by the first gas distributor intopredetermined flow ratios as a first gas to be introduced through theinner gas holes and a first gas to be introduced through the outer gasholes.

O₂ and N₂ are supplied via gas flow controllers 13-9 and 13-10 atpredetermined flow rates to reach a second gas distributor 14-2. Thegases that have reached the second gas distributor 14-2 are called asecond gas. The second gas is divided by the second gas distributor intopredetermined flow ratios, wherein one flow is mixed at a gas junction15-1 with the first gas to be introduced through the inner gas holes andthe other is mixed at a gas junction 15-2 with the first gas to beintroduced through the outer gas holes.

A turbo molecular pump 25 is connected via a gate valve 24 to theprocessing chamber 1 to decompress the processing chamber 1, enablingthe chamber 1 to be maintained at predetermined pressure while theprocessing gas is supplied thereto. A dry pump 26 is connected to theexhaust side of the turbo molecular pump 25.

Next, the procedure for uniformizing the process depth and the criticaldimension across the wafer plane will be explained, taking deep holeetching of an SiOC film as an example. CF₄ and CHF₃ were used as thefist gas, and the flow rates of CF₄ and CHF₃ were each set to 20 ccm atthe gas flow controllers 13-2 and 13-6. N₂ was used as the second gas,and the flow rate thereof was set to 100 ccm at the gas flow controller13-10.

At first, the processing gas introduced through the inner gas holes andthe processing gas introduced through the outer gas holes are set tohave the same composition, and etching was performed without carryingout any plasma distribution control through the magnetic field. The gasflow in the gas supply system is illustrated in FIG. 3. The first gasdistributor 14-1 divides 40 ccm of mixed gas containing CF₄ and CHF₃equally into 20 ccm, and the second gas distributor 14-2 divides N₂equally into 50 ccm. The wafer in-plane distribution of the processdepth and the critical dimension of the hole bottom of this example areillustrated in FIG. 2(A). The etching rate is higher at the center ofthe wafer and lower at the outer periphery of the wafer, and the holesare deeper at the wafer center where the hole bottom critical dimensionis smaller than at the outer periphery of the wafer.

Next, plasma distribution was controlled via the magnetic field touniformize the process depth across the wafer plane. The wafer in-planedistribution of the process depth and hole bottom critical dimensionaccording to this example is illustrated in FIG. 2(B). As shown, byapplying a magnetic field, the in-plane distribution of the etching ratecan be uniformized, and thus the in-plane distribution of the processdepth can also be uniformized. On the other hand, the hole bottomcritical dimension is still small at the wafer center, which is presumedto be caused by the excessive thickness of the deposition film or thelarge amount of deposition of etching inhibitors at the wafer center.

Next, as shown in FIG. 4, 10 ccm each of CF₄ and CHF₃ were introducedinto the processing chamber uniformly through the inner and outer gasholes, respectively, and N₂ which contributes to removal of thedeposition film is introduced at flow rates of 80 ccm from the inner gasholes and 20 ccm from the outer gas holes, while performing plasmadistribution control through the magnetic field. At this time, the firstgas distributor 14-1 divides the mixed gas of 40 ccm composed of CF₄ andCHF₃ equally into 20 ccm, and the second gas distributor 14-2 divides N₂into flow ratios of 8:2. In other words, the first gas distributor 14-1and the second gas distributor 14-2 control the ratio of flow of N₂supplied through the inner gas holes and N₂ supplied through the outergas holes into the processing chamber, without changing the flow rate ofCF₄ and CHF₃ supplied through the inner and outer gas holes into theprocessing chamber. The wafer in-plane distribution of the process depthand the hole bottom critical dimension according to the present exampleis illustrated in FIG. 2(C). Through comparison with FIG. 2(B), it canbe seen that the hole bottom critical dimension can be uniformizedacross the wafer plane without changing the in-plane uniformity of theprocess depth.

According to the above explanation, the first gas distributor 14-1divides the first gas evenly, but it is also possible to adjust the gasdistribution ratio of the first gas distributor 14-1 during the state ofFIG. 2(B) to control the flow ratio of the first gas supplied throughthe inner gas holes and through the outer gas holes, in order to furtherenhance the process depth uniformity. However, the in-plane uniformityof the critical dimension may change by enhancing the process depthuniformity through adjustment of the distribution ratio of the first gasdistributor 14-1, so it is preferable to adjust the first gasdistribution ratio of the first gas distributor 14-1 before uniformizingthe in-plane distribution of the critical dimension.

As described above, it has been shown that in the processing of SiOC,the process depth can be uniformized by the magnetic field and the holebottom critical dimension can be uniformized by adjusting the flow ratioof N₂ introduced through the inner and outer gas holes. In the etchingof SiO₂ or SiOF, Ar, CF-based gas such as C₄F₈, and O₂ are used, forexample, and in such case, the distribution ratio of O₂ can be adjustedthrough the second gas distributor 14-2 to thereby uniformize the holebottom critical dimension and other critical dimensions across the waferplane while maintaining a uniform wafer in-plane process depth.

Now, we will describe the method for confirming the operation of the gasdistributors. Gas flowmeters 22-1 and 22-2 are disposed between thefirst gas distributor 14-1 and processing chamber 1, and gas flowmeters22-3 and 22-4 are disposed between the second gas distributor 14-2 andprocessing chamber 1. By comparing the gas distribution ratio set forthe first gas distributor 14-1 and the flow ratio of gas flowmeters 22-1and 22-2 while supplying the first gas, for example, it is possible tocheck whether the first gas distributor 14-1 is operating normally ornot.

Further, by supplying only the second gas and not supplying the firstgas, it is possible to check whether the second gas distributor 14-2 isoperating normally or not by comparing the gas distribution ratio setfor the second gas distributor 14-2 and the flow ratio of gas flowmeters22-3 and 22-4.

Moreover, valves 23-1 and 23-2 are disposed downstream from the firstgas distributor 14-1 and the second gas distributor 14-2 and upstream ofthe processing chamber 1, and the gas pipes equipped with the valves23-3 and 23-4 are branched at the upstream side of the valves anddownstream side of the gas flowmeters 22-3 and 22-4, to enable theprocessing gases to be bypassed to the dry pump 26 and evacuatedtherethrough, for example, without passing through the processingchamber 1, so that the operation of the gas distributors can be checked.The procedure for this operation check will be described hereinaftertaking the first gas distributor 14-1 as the example.

First of all, valves 23-1 and 23-4 are opened and valves 23-2 and 23-3are closed, so that the processing gas to be supplied through the innergas holes is introduced to the processing chamber 1, and the processinggas to be supplied through the outer gas holes normally is evacuatedthrough the dry pump 26 without passing through the processing chamber1. Thereafter, the gate valve 24 and valve 23-5 are closed, and 500 ccmsof Ar gas is supplied, for example. The gas distribution ratio at thefirst gas distributor 14-1 is set to a.b, for example. The flow rate ofAr gas introduced through the inner gas holes into the processingchamber 1 can be calculated based on the volume of the processingchamber 1 and the pressure rising speed, and the calculated value is setas A.

Next, valves 23-2 and 23-3 are opened and valves 23-1 and 23-4 areclosed, so that the processing gas to be supplied through the inner gasholes normally is evacuated through the dry pump 26 without beingintroduced to the processing chamber 1 while the processing gas to besupplied through the outer gas holes is introduced into the processingchamber 1. Then, 500 ccm of Ar gas is supplied and the flow ratio of thesecond gas distributor 14-1 is set as it is to a:b. The flow rate of Argas can be calculated based on the capacity of the processing chamber 1and the pressure rising speed, and the calculated flow rate is set as B.Thereafter, by comparing the ratio of A:B and a:b, it is possible toconfirm whether the first gas distributor 14-1 is operating normally ornot.

The first embodiment has been explained up to now, but the control ofgas supply similar to that of the first embodiment can be performedwithout using gas distributors. Thus, a second embodiment of the presentinvention will now be explained with reference to FIG. 5. In FIG. 5, theexplanations on the portions equivalent to those of FIG. 1 are omitted.The present embodiment comprises gas flow controllers 13-11 through13-20, one for each processing gas, for controlling the amount ofprocessing gas supplied through the inner gas holes, and gas flowcontrollers 13-1 through 13-10 for controlling the amount of processinggas supplied through the outer gas holes. As can be seen throughcomparison with FIG. 1, the necessary number of gas flow controllers 13is greater compared to the example where the gas distributors 14 areadopted, but the gas supply can be controlled similarly as FIG. 1.

The first and second embodiments described above have illustrated casesin which the present invention was applied to the parallel plate ECRplasma processing apparatus having a large degree of freedom incontrolling the plasma distribution via the magnetic field. However, thepresent invention can be widely applied to plasma processing apparatusesthat control the uniformity of plasma distribution through means otherthan magnetic fields.

As an example, a third embodiment of the present invention will now bedescribed. FIG. 6 illustrates an example in which the present inventionis applied to a CCP (capacitively coupled plasma) type plasma processingapparatus. The present apparatus radiates electromagnetic waves with afrequency in the range between 10 and 200 MHz from the electromagneticradiation antenna, and generates plasma by the RF electric fieldgenerated between electrodes. The electromagnetic radiation antenna isdivided into two parts, for example, an inner antenna 3-1 and an outerantenna 3-2, and by changing the ratio of PT. powers radiated from theinner and outer antennas 31 and 32 via an RF power distributor 17, thefreedom of centrol of plasma distribution is increased. An electrode 4on which an object 2 to be processed is placed is disposed within aprocessing chamber 1, and an RF power supply 5C is connected to theelectrode 4 via a matching network 6C for controlling the flux andincident energy of ions being incident on the object 2 to be processed.According to the third embodiment shown in FIG. 6, the combination ofgas flow controllers and gas distributors 14-1 and 14-2 are the same asthat of the first embodiment, but a gas supply system similar to that ofthe second embodiment can also be adopted.

FIG. 7 is an enlarged view showing the portion where the gas dispersionplate 10 is divided into two areas, one area for dispersing theprocessing gas introduced through the inner gas holes into theprocessing chamber, and the other area for dispersing the processing gasintroduced through the outer gas holes into the processing chamber.According to the third embodiment, two gas dispersion plates 10-1 and10-2; one superposed on the other, are used to disperse the processinggas. The gas dispersion plates 10-1 and 10-2 are divided into two areas,respectively, with ring-shaped partitions (for example, O-rings) 12-1and 12-2. Moreover, the gas dispersion plates 10-1 and 10-2 are screwedusing a screw 32 onto the antenna 3 via an aluminum spacer 33, forexample, in order to prevent the gas dispersion plates 10-1 and 10-2from being bent by the thickness of the O-rings. Furthermore, the gasdispersion plates 10-1 and 10-2 and the antenna 3 are separated via aninsulator 31 so as to enable different RF power to be suppliedrespectively via an inner antenna 3-1 and an outer antenna 3-2.

The supply of gas and input of RF power to the antenna 3 will bedescribed with reference to FIG. 6 and FIG. 8 illustrating the shape ofthe antenna 3 seen from the upper direction of the processing chamber.The RF power supplied to the inner antenna 3-1 is fed via a powerconnect portion 34-1 positioned substantially at the center of the innerantenna 3-1. The RF power supplied to the outer antenna 3-2 is fed viapower connect portions 34-2 positioned substantially along thecircumference of the outer antenna 3-2.

The processing gas to be introduced through the inner gas holes into theprocessing chamber is led through the gas inlet 35-1 provided so as notto overlap with the power connect portion 34-1 to the inner side of theinner antenna 3-1, then through the gas flow path 27-1 provided in theantenna and out through the gas outlet 36-1 provided substantially atthe center of the antenna onto the upper surface of the gas dispersionplate 10-1. The processing gas to be introduced through the outer gasholes into the processing chamber is led from above the outer antenna3-2 through the gas inlet 35-2 provided to the antenna and through thegas flow path 27-2 provided in the outer antenna 3-2 to be ejected fromthe gas outlet 36-2 onto the upper outer surface of the gas dispersionplate 10-1. In order to uniformly supply the processing gas to beintroduced through the outer gas holes into the processing chamberthrough the gas holes provided to the outer side of the shower plate,plural gas inlets 35-2 are arranged substantially concentrically forleading into the antenna the processing gas to be introduced through theouter gas holes into the processing chamber. Further, in order touniformly disperse the processing gas to be introduced into theprocessing chamber through the outer gas holes at the outer area of thegas dispersion plate 10-1, plural gas outlets 36-2 are arrangedsubstantially along the circumference of the outer antenna 3-2 forejecting the processing gas onto the gas dispersion plate.

In order to etch the object to be processed uniformly across the planethereof according to the present apparatus, at first, the power ratio ofRF power radiated via the inner and outer antennas 3-1 and 3-2 arecontrolled, for example, to uniformize the process depth across theplane of the object. Thereafter, the flow ratio of O₂ or N₂ gasintroduced through the inner and outer gas holes into the processingchamber is controlled so as to uniformize the critical dimension acrossthe plane of the object while maintaining a uniform process depth.

Next, the fourth embodiment of the present invention will be describedwith reference to FIG. 9. According to the apparatus of the presentembodiment, two RF power supplies 5A and 5C with different frequenciesare connected to the electrode 4 via matching networks 6A and 6C,respectively. The present apparatus generates plasma through the RFpower supplied from the RF power supplies 5A and 5C and controls thedistribution of plasma by the balance of power output from the RF powersupplies 5A and 5C.

In order to perform uniform etching across the plane of the objectaccording to the present apparatus, for example, the balance between theoutput power of RF power supply 5A and the output power of RF powersupply 5C is adjusted to control the plasma distribution and touniformize the process depth across the plane of the object. Thereafter,by controlling the flow ratio of O₂ or N₂ supplied via gas outlets 36-1and 36-2 of the top plate and through the inner gas holes and the outergas holes of the shower plate 11 into the processing chamber 1, thecritical dimension can be uniformized across the plane of the objectwhile maintaining a uniform process depth across the plane of theobject.

The embodiments of the present invention have been described up to nowwith respect to various plasma sources, but the present invention is notlimitedly applied to the described plasma sources, and can be appliedwidely to other plasma processing apparatuses.

1. A method for checking a gas distributor in a plasma processingapparatus comprising a processing chamber, an evacuation means fordecompressing the processing chamber, an electrode on which an object tobe processed is placed, an electromagnetic radiation power supply, afirst gas inlet, a second gas inlet, and a gas distributor, the methodcomprising: providing gas lines between the gas distributor and thefirst gas inlet and between the gas distributor and the second gas inletfor evacuating a processing gas without passing through the processingchamber; supplying one processing gas divided by the gas distributorinto the processing chamber, evacuating the other processing gas withoutpassing through the processing chamber, and calculating a flow rate ofthe one processing gas based on a capacity of the processing chamber anda pressure rising speed in the processing chamber; supplying the otherprocessing gas divided by the gas distributor into the processingchamber, evacuating the one processing gas without passing through theprocessing chamber, and calculating a flow rate of the other processinggas based on the capacity of the processing chamber and the pressurerising speed in the processing chamber; and checking a normality of thegas distributor utilizing the ratio between the flow rate of the oneprocessing gas and the flow rate of the other processing gas.